IBM Support

IT17458: IN DB2 DPF, POSSIBLE WRONG RESULT WHEN OUTER JOIN PREDICATE COL1=COL2 AND BOTH COLUMNS ARE FROM THE OUTER TABLE

Subscribe

You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • DB2 can return wrong query result when all of the following
    conditions are satisfied
    
    1. DPF (Data Partitioning Feature) environment.
    2. The query has a outer join, and the outer join has a
    predicate of the form COLUMN1=COLUMN2, where both columns are
    from the outer table.
    3. Either DB2COMPOPT=OJLOCALPRDPLANNING is set, or the
    NULL-producing side of the outer join is a CSE (Common
    SubExpression), UNION, GROUP-BY, or another outer join.
    4. The query has a key requirement or order requirement on one
    of the columns in the COLUMN1=COLUMN2 predicate.
    
    For example:
    
    The following query can possibly produce a wrong result in DPF
    environment, because the query has an outer join predicate of
    TT.T1_C1 = TT.T1_C2, the NULL-producing side of the outer join
    is another outer join, and the query requires "DISTINCT
    TT.T1_C2"
    
    SELECT DISTINCT TT.T1_C2 FROM T1 TT LEFT OUTER JOIN
    (SELECT T2.T2_C4 FROM T2 FULL OUTER JOIN T1 ON T1.T1_C1 =
    T2.T2_C2) TT2 on TT.T1_C1 = TT.T1_C2
    
    The following query can possibly produce a wrong result in DPF
    environment and when DB2COMPOPT=OJLOCALPRDPLANNING is set,
    because the query has an outer join predicate of
    T1.T1_C1=T1.T1_C2, and the query requires "ORDER BY TT.T1_C2"
    
    SELECT * FROM T2 TT1, (SELECT * FROM T1 LEFT JOIN T2 on
    T1.T1_C1=T1.T1_C2 ) TT
    WHERE TT1.T2_C4 = TT.T1_C1
    ORDER BY TT.T1_C2
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * DB2 DPF                                                      *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 Version 11.1.1.1                              *
    ****************************************************************
    

Problem conclusion

  • First fixed in DB2 Version 11.1.1.1
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT17458

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-10-12

  • Closed date

    2016-12-20

  • Last modified date

    2016-12-20

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

    IT17505 IT17506 IT17507 IT17512

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
29 June 2020